Irrigation systems are sometimes automated so that they can irrigate large fields, or portions of fields, largely without human action or intervention. To this end, such irrigation systems may include one or more sets of tires that enable the irrigation system to be moved to different locations in the field that is being irrigated. Movement of the irrigation system may be performed by way of a drive system coupled to the tires.
While the one or more sets of tires enable the repositioning of the irrigation system, the use of tires can present a variety of problems. One such problem is that, due to the weight of an irrigation system, particularly when filled with water, as well as to the relatively large size of the tires, the tires often make tracks in the soil of the irrigated field that are quite deep and/or wide. These tracks, which are sometimes referred to as pivot tracks, can make it quite difficult for other equipment, such as harvesters, trucks and tractors for example, to travel through the field.
As well, when one or more irrigation systems are moved, such tracks can make it difficult, or impossible, for the wheels of other irrigation systems to travel through the field. Moreover, these irrigation systems can experience significant wear and tear as they attempt to navigate through and over the tracks left by another irrigation system.
Another example of problems presented by the use of tires in an irrigation system concerns the field itself. In particular, the tracks created by such tires can cause soil erosion in the field. The erosion can be aggravated further if the tire tracks become filled with water and muddy, as commonly occurs.
A related problem is that the relatively wide configuration of the tires results in a corresponding reduction in the amount of field space that is available for growing. Depending upon the size of the irrigation system, and number and size of associated tires, this reduction can be quite significant in some cases.
In addition to the problems noted above, the tires themselves are inherently prone to various problems. For example, the tires typically employed in irrigation systems are pneumatic. Thus, the rubber tire material is prone to deterioration due to long exposure to the sun, and pneumatic tires may go flat as a result of valve failure or contact with a sharp object. Regardless of the failure mechanism, the tire then has to be repaired or replaced, which may be time-consuming and expensive. For example, the repair of replacement of one or more tires introduces undesirable down time for the irrigation system. This down time can be particularly problematic, for example, in hot weather conditions where an adequate flow of water is critical to the survival of the crop.
Moreover, if a tire goes flat, a farmer may not become immediately aware of the problem and, as a result, the irrigation system may continue to operate with the flat tire, or flat tires. This can put undue wear and tear on the irrigation system, including components of the drive system such as linkages and bearings, as the irrigation system moves through the field.
Moreover, even if a tire does not go flat, problems can still occur. For example, if adequate pressure is not maintained in the tire, the performance of the tire will suffer and it may be relatively more difficult for the tire to move through the field than would be the case if the tire were at the correct pressure. This problem can be aggravated further by the condition of the field where the irrigation system is employed.
As well, it should be apparent that when the foregoing problems occur in large growing operations that include numerous irrigation systems and associated tires, these problems present a significant cumulative impact on time, productivity, and finances.
Some efforts to resolve problems such as those noted above involve the use of a track that rotates around two pneumatic tires. Although such an arrangement may result in a somewhat less problematic track shape, these arrangements introduce their own set of problems. For example, the use of pneumatic tires is problematic for the reasons already stated.
As well, because these track and tire arrangements may rely on a high level of track tension for useful operation, the use of equipment such as tensioners is required. These tensioners however can impose tremendous stress on components such as shafts, bearings and gearboxes, thus reducing the useful life of those components. As well, the tensioners may be vulnerable to changes in tire pressure, such that the tension can vary with the tire pressure. Moreover, tire pressure can change dramatically throughout the course of the day and performance of the track and tire arrangement will vary accordingly. A related problem is that there is no easy way for a farmer or other user to monitor, and effect changes in tire pressure should there be a need to do so.
Finally, track and tire configurations that employ rubber tracks present still further problems. For example, rubber tracks can degrade after prolonged exposure to sun and heat. Replacement of these rubber tracks introduces further expense in the form of parts, labor, and irrigation system down time.
In light of problems such as these, it would be useful to have an irrigation system, such as a pivot irrigation system, for example, that was configured in such a way that at least some of the problems associated with the use of tires may be avoided.